One of the last frontiers of nature has yielded more than 350 new species of animals and plants in just the last 10 years. The eastern Himalayas contain vast tracts of remote and inaccessible terrain that few scientists have managed to reach and which provide a home for some of the planet's most mysterious animals.

New species are turning up at a rate of 35 a year and highlights uncovered in the region since 1998 include the miniature muntjac (
Muntiacus putaoensis), also known as the leaf deer, which at 60 to 80cm tall and 11kg is the smallest species of deer in the world, and the Arunachal macaque (
Macaca munzala) – the first new monkey to be found in a century.

Among the most visually striking are the red-footed but otherwise bright green flying frog (
Rhacophorus suffry) and Smith's litter frog (
Leptobrachium smithi), which boasts huge golden eyes and was described by the WWF, which has compiled a report on the region, as "among the most extraordinary-looking" frogs in the world.

Other new species include catfish with sticky stomachs, a luridly green pit viper, a freshwater beetle living at 5,100 metres above sea level – higher than any other beetle – and a bird restricted to a site less than a square mile.

Overall, from 1998 to 2008, two mammals, two birds, 16 amphibians, 16 reptiles, 14 fish, 244 plants and more than 60 invertebrates have been identified in the region, according to the WWF report, The Eastern Himalayas – Where Worlds Collide.

The area is already the stronghold of the Bengal tiger, the only home of the snow leopards and the last sanctuary of the greater one-horned rhino, but has so much unknown wildlife that researchers expect many more discoveries to be made in the future.

The eastern Himalayas – divided between Nepal, Bhutan and parts of China, India, Bangladesh and Burma – is regarded as one of the most rugged and beautiful areas of the world.

Mark Wright of WWF said: "The exciting thing about this is it is so easy to fall into the trap of thinking we know everything about the world. But this report shows there's still a huge amount out there about which we know almost nothing. Even once we've ticked the box of identifying a species we have only just scratched the surface of what there is to know."

Although they have only just been discovered, the new animals and plants are already under threat, as are many thousands of other species in the region. "While we can be really happy and excited about finding them, the elephant in the room is climate change," he said. "We know that along with the Poles, mountain areas are going to be the regions most heavily impacted by climate change. The data we have suggests it's warming in the Himalayas far faster than the global average."

The impacts, such as the spread of disease, the destruction of crops and the large migrations of people desperate to move to other parts of the world, will eventually be felt as far away as the UK.

"One in five of all mankind gets its river water from the water that rises in the Himalayas. One way or another, that's going to come back to haunt us in the UK at some stage. We will have to pick up the cost."

Discoveries have also been made of species which lived in the region millions of years ago and were preserved when they became encased in amber resin.

Among the creatures preserved in amber was the earliest known gecko (
Cretaceogekko burmae), from 100 million years ago which was identified in 2008. Others included the oldest known tick and the earliest recorded mushroom.

The region is a hotspot for wildlife and harbours a huge number of species including 10,000 plants, 300 mammals, 977 birds, 176 reptiles, 105 amphibians and 269 types of freshwater fish. WWF has launched the Climate for Life campaign to raise public awareness of environmental problems in the Himalayas and is working with local communities to help them cope with the impacts of climate change.

The wealth and variety of wildlife being found in the region makes the eastern Himalayas comparable with better recognised ecological hotspots such as Borneo.

However, despite its remoteness only 25 per cent of the original habitat remains intact and the plants and animals face threats including illegal logging, the spread of agriculture, poaching and pollution.